A large body of evidence suggests that ion channels act as force sensors in mechanotransduction systems. In flies, the No mechanoreceptor potential-C (Nomp-C) channel has been suggested to be a force transduction channel in neurons that detect bristle deflection. In C. elegans, mechanotransduction channels of the Deg/ENaC family have been unambiguously identified as force sensors in touch neurons. The Mec10/Mec4 channel is the central component of a transduction complex that also involves extracellular matrix proteins. In bacteria, a simpler form of mechanotransduction involves a mechanosensitive channel of large conductance (MscL) and another of smaller conductance (MscS). These bacterial force-sensing channels detect membrane stretch triggered by osmotic pressure and protect the cell from rupture by allowing emergency ejection of osmolytes. Despite progress in identifying these important channels, the identities of mechanotransduction channels in vertebrate neurons remain elusive. For example, orthologs of Nomp-C and Msc channels have not been found in mammals and there is limited evidence supporting a role for Deg/ENaC's in mammalian mechanotransduction. Since it is likely that molecular mechanisms of mechanotransduction are ancient, and evolutionarily conserved, we hypothesize that additional mechanotransduction channels have yet to be identified. The goal of this proposal is to identify candidates for these evolutionarily conserved mechanotransduction channels. To achieve this we will: 1) Test the hypothesis that predicted ion channel subunits of the Drosophila genome function in mechanotransduction by performing tissue-specific RNAi knock down of the ion channel RNAs in mechanosensory neurons. 2) Use optogenetic techniques to separate channels that are likely to act at the transduction step from those that function downstream of transduction. 3) Begin detailed genetic analysis of the mechanosensory ion channels that we have identified in the first two aims. Identifying the novel mechanotransduction channels and their vertebrate homologues may lead to an increased understanding of human diseases ranging from deafness to pain. PUBLIC HEALTH RELEVANCE: Identifying the novel mechanotransduction channels and their vertebrate homologues may lead to an increased understanding of human diseases ranging from deafness to pain.